package com.hmdp.service.impl;

import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
*@Author: X_x
*@Date: 2024-08-22-22-38
*@Description:  * @param null
*@return:
*@tags: 梦想和爱 健康和学习
*/
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Object queryById(Long id) {
        //缓存穿透
//        Shop shop = cacheClient
//                .queryWithPassThrough(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);
        //互斥锁解决缓存击穿
//        Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        Shop shop = cacheClient
                .queryWithLogicalExpire(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.SECONDS);

        if (shop == null) {
            return Result.fail("店铺不存在！");
        }
        //返回
        return Result.ok(shop);
    }

    /**
     * 缓存击穿：逻辑过期
     */
    //创建一个线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
/*
    public Shop queryWithLogicalExpire(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3.未命中，直接返回null
            return null;
        }

        //4.命中，需要先把Json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.1未过期，直接返回店铺信息
            return shop;
        }

        //5.2已过期，需要缓存重建
        //6.缓存重建
        //6.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //6.2判断是否获取锁成功
        if (isLock) {
            //6.3成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw  new RuntimeException(e);
                }finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }

        //6.4失败，返回过期的商铺信息
        return shop;

    }*/
    /**
     * 缓存穿透：不存在的数据请求直接访问数据库，数据库压力增大导致宕机
     */
    /*public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断是否命中空值
        if (shopJson != null) {
            //返回一个错误信息
            return null;
        }
        //4.不存在，根据id查询数据库
        Shop shop = getById(id);
        //5.数据库不存在，返回错误
        if (shop == null) {
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key, "",CACHE_NULL_TTL,TimeUnit.MINUTES);
            //返回错误信息
            return null;
        }
        //6.存在，写入redis缓存
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return shop;

    }*/

    /**
     * 互斥锁=>缓存击穿：热点数据失效
     */
    /*public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断是否命中空值
        if (shopJson != null) {
            //返回一个错误信息
            return null;
        }

        //4.实现缓存重建
        //4.1 获取互斥锁
        String lockKey = "lock:shop:" + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2 判断是否获取成功
            if (!isLock) {
                //4.3 失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4 不存在，根据id查询数据库
            shop = getById(id);

            //模拟重建延时
            Thread.sleep(200);
            //5.数据库不存在，返回错误
            if (shop == null) {
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key, "",CACHE_NULL_TTL,TimeUnit.MINUTES);
                //返回错误信息
                return null;
            }
            //6.存在，写入redis缓存
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {

            //7.释放互斥锁
            unlock(lockKey);
        }

        //8.返回
        return shop;

    }*/

    /**
     * 尝试获取锁
     */
    /*private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }*/

    /**
     * 释放锁
     */
   /* private void unlock(String key){
        stringRedisTemplate.delete(key);
    }
    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }*/
    @Override
    @Transactional
    public Result update(Shop shop) {
        //先更新数据库，再删除缓存
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("商铺id不能为空！");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }
    /**
     * 根据商铺类型分页查询商铺信息
     * @param typeId 商铺类型
     * @param current 页码
     * @return 商铺列表
     */
    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1. 判断是否需要根据距离查询
        if (x == null || y == null) {
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //2. 计算分页查询参数
        int from = (current - 1) * SystemConstants.MAX_PAGE_SIZE;
        int end = current * SystemConstants.MAX_PAGE_SIZE;
        String key = SHOP_GEO_KEY + typeId;
        //3. 查询redis、按照距离排序、分页; 结果：shopId、distance
        //GEOSEARCH key FROMLONLAT x y BYRADIUS 5000 m WITHDIST
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end));
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        //4. 解析出id
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() < from) {
            //起始查询位置大于数据总量，则说明没数据了，返回空集合
            return Result.ok(Collections.emptyList());
        }
        ArrayList<Long> ids = new ArrayList<>(list.size());
        HashMap<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        //5. 根据id查询shop
        String idsStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD( id," + idsStr + ")").list();
        for (Shop shop : shops) {
            //设置shop的举例属性，从distanceMap中根据shopId查询
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        //6. 返回
        return Result.ok(shops);
    }
}
